1. Field of the Invention
The present invention relates generally to inverters that convert Direct Current (DC) to Alternating Current (AC). More particularly, the present invention relates to a micro-inverter that dynamically selects conversion parameters for converting DC to AC.
2. Description of the Related Art
Historically, solar panels have been used mostly in remote applications where commercial power was not available. This was due to the high cost of an installation making it an economical choice only when nothing else was available. However, it is now well established that the fossil energy reserves, which are currently used to generate electricity, are being rapidly depleted. The worldwide growth of power demand is leading to a durable increase in energy cost. Short of the development of a clean nuclear fusion process, there is no foreseeable end to such trend.
Photovoltaic generation systems require an inverter that converts Direct Current (DC) from solar cells to Alternating Current (AC) for use by household appliances, for example. It is important for any power generation system to produce and deliver electricity to electric appliances in the most efficient manner. A typical photovoltaic array comprises a plurality of sub-arrays, where each sub-array comprises coupled individual solar panels. A junction box combines the output of the various sub-arrays to form a DC signal that is supplied to an inverter. The inverter converts the DC to AC and supplies the AC to the power grid. The user uses power from the grid in a typical fashion; however, their cost of electricity from the grid is offset by the amount of electricity the photovoltaic generation system supplies to the grid.
In such a system, the amount of power that is efficiently coupled to the grid is important for the cost recovery of the system. As such, the inverter must be as efficient as possible.
To enhance the overall efficiency, present technology uses “micro-inverters”, such that each solar panel is coupled to an individual inverter. The AC outputs of the micro-inverters are combined and coupled to the power grid. Although the use of micro-inverters is more efficient than a single inverter, the efficiency of each individual micro-inverter is typically 90% or less.
Therefore, there is a need for a method and apparatus for efficiently converting DC to AC.